<template>
    <div class="s-canvas">
        <canvas id="s-canvas" :width="contentWidth" :height="contentHeight"></canvas>
    </div>
</template>
<script>
    export default {
        name: "SIdentify",
        props: {
            identifyCode: {
                type: String,
                default: "1234"
            },
            fontSizeMin: {
                type: Number,
                default: 35
            },
            fontSizeMax: {
                type: Number,
                default: 35
            },
            backgroundColorMin: {
                type: Number,
                default: 180
            },
            backgroundColorMax: {
                type: Number,
                default: 240
            },
            colorMin: {
                type: Number,
                default: 50
            },
            colorMax: {
                type: Number,
                default: 160
            },
            lineColorMin: {
                type: Number,
                default: 100
            },
            lineColorMax: {
                type: Number,
                default: 200
            },
            dotColorMin: {
                type: Number,
                default: 0
            },
            dotColorMax: {
                type: Number,
                default: 255
            },
            contentWidth: {
                type: Number,
                default: 120
            },
            contentHeight: {
                type: Number,
                default: 40
            }
        },
        methods: {
            // 生成一个随机数
            randomNum(min, max) {
                return Math.floor(Math.random() * (max - min) + min);
            },
            // 生成一个随机的颜色
            randomColor(min, max) {
                let r = this.randomNum(min, max);
                let g = this.randomNum(min, max);
                let b = this.randomNum(min, max);
                return "rgb(" + r + "," + g + "," + b + ")";
            },
            transparent() {
                return "rgb(255,255,255)";
            },
            drawPic() {
                let canvas = document.getElementById("s-canvas");
                let ctx = canvas.getContext("2d");
                ctx.textBaseline = "bottom";
                // 绘制背景
                ctx.fillStyle = this.randomColor(
                  this.backgroundColorMin,
                  this.backgroundColorMax
                );
                ctx.fillStyle = this.transparent();
                ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
                // 绘制文字
                for (let i = 0; i < this.identifyCode.length; i++) {
                    this.drawText(ctx, this.identifyCode[i], i);
                }
                this.drawLine(ctx)
                this.drawDot(ctx)
            },
            drawText(ctx, txt, i) {
                ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
                ctx.font =
                    this.randomNum(this.fontSizeMin, this.fontSizeMax) + "px SimHei";
                let x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
                let y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
                var deg = this.randomNum(-10, 10);
                // 修改坐标原点和旋转角度
                ctx.translate(x, y);
                ctx.rotate((deg * Math.PI) / 180);
                ctx.fillText(txt, 0, 0);
                // 恢复坐标原点和旋转角度
                ctx.rotate((-deg * Math.PI) / 180);
                ctx.translate(-x, -y);
            },
            drawLine(ctx) {
                // 绘制干扰线
                for (let i = 0; i < 8; i++) {
                    ctx.strokeStyle = this.randomColor(
                        this.lineColorMin,
                        this.lineColorMax
                    );
                    ctx.beginPath();
                    ctx.moveTo(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight)
                    );
                    ctx.lineTo(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight)
                    );
                    ctx.stroke();
                }
            },
            drawDot(ctx) {
                // 绘制干扰点
                for (let i = 0; i < 100; i++) {
                    ctx.fillStyle = this.randomColor(0, 255);
                    ctx.beginPath();
                    ctx.arc(
                        this.randomNum(0, this.contentWidth),
                        this.randomNum(0, this.contentHeight),
                        1,
                        0,
                        2 * Math.PI
                    );
                    ctx.fill();
                }
            }
        },
        watch: {
            identifyCode() {
                this.drawPic();
            }
        },
        mounted() {
            this.drawPic();
        }
    };
</script>
